Wales scrum-half Gareth Cooper made his Test debut against Italy in Rome in 2001 whilst playing his club rugby for English side Bath. Cooper's early years had been spent with Pencoed RFC before he made the switch across the Severn Bridge to the West Country.

After making his debut Cooper toured Japan with Wales before nailing down the Wales scrum-half jersey as his own before the 2003 Rugby World Cup in Australia. Cooper made five appearances during the tournament as Wales were knocked out at the quarter-final stage.

Cooper returned to Wales to play for the newly-formed Celtic Warriors in 2003 but as Wales improved through the 2004 Six Nations he found himself scrapping for the Test jersey with Scarlets scrum-half Dwayne Peel.

Cooper joined Newport Gwent Dragons in 2004, but the change in scenery couldn't rejuvenate his form as Peel secured the scrum-half berth as Wales racked up a Grand Slam in 2005, leaving Cooper on the bench. Despite falling out-of-favour with Wales Cooper was selected for the 2005 British and Irish Lions tour of New Zealand, playing the warm-up Test against Argentina at the Millennium Stadium before finding himself behind Peel and Scotland's Chris Cusiter in the pecking order on tour.

Cooper struggled to fight his way into the Wales reckoning following the Lions tour, with Mike Phillips also edging ahead of him in the scrum-half stakes. Cooper announced in March 2007 that he would be joining Guinness Premiership side Gloucester at the start of the 2007-08 season.

Cooper made his second Rugby World Cup in 2007, but was limited to a single replacement appearance against Japan. Cooper was an unused squad member as Wales again secured a Grand Slam in 2008, before injuries to both Peel and Phillips offered him another shot at the Wales jersey for their summer tour to South Africa.

Cooper played both Tests, scoring an excellent individual try in the second. He then kept Peel on the bench for Wales' autumn internationals, including a win over Australia at the Millennium Stadium.

In January 2009 Cooper was announced alongside Phillips as Wales' scrum-halves for the 2009 Six Nations, but injury prevented him from taking any part in the tournament. In March 2009 he announced that he would be joining Cardiff Blues for the 2009-10 season but failed to make a mark at the region due to a groin injury. In November 2010 he left the Blues in order to take a six to 12-month rest.